Computer cooler

ABSTRACT

The invention is a solid-state thermoelectric cooling device for attachment to a personal or laptop computer. The device consists of a plurality of thermoelectric coolers that are mounted on a heat exchanger, each powered by less than about 12 volts DC, which provides a cold face on a thermoelectric cooling panel which is mounted on the top or a side of the computer. The internal temperature of the computer is controlled to avoid moisture condensation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to cooling electronic devices and, in particular,to using thermoelectric devices to cool microprocessors, graphicsprocessors, and other computer components.

2. Description of Related Art Including Information Disclosed Under 37CFR 1.97 and 1.98

In recent years, devices and integrated circuits used in informationprocessing apparati, such as personal computers and servers, tend togenerate an increasing amount of heat because of their ever-increasingintegration. CPUs increase the amount of heat produced because of theirfaster operation frequencies and enhanced integration.

Conventional personal computers and servers commonly employ a method ofattaching a heat sink to the CPU to transfer the heat of the CPU to theheat sink and cooling the heat sink. To dissipate heat to the outside ofthe computer, a cooling fan may provide forced air cooling.

The cooling capacity is enhanced by enlarging the heat sink andincreasing the airflow of the cooling fan. The enlarged heat sink leadsto an increase in the size of the computer while the increased airflowof the cooling fan also results in a size increase of the computer dueto the enlarged cooling fan. Airflow may be increased by increasing thespeed of the fan, although this tends to increase fan noise.

Radiating heat generated by a CPU or the like that replace the heat sinkinclude a heat pipe and a liquid-cooling system that transport heat by acoolant. These methods feature an increased degree of freedom in thestructure because the coolant is cooled at a location remote from aheat-generating source such as CPU. In a case where a cooling fan isused to radiate the coolant-carried heat outside the equipment problemssimilar to those described above arise.

Various methods have been proposed as solution for these problems. It isknown to use air cooling and liquid cooling. However, these techniquesare complex or noisy.

BRIEF SUMMARY OF THE INVENTION

A cooling panel that attachable to a personal computer case; where thecooling panel is comprised of a number of solid-state thermoelectriccoolers. The thermoelectric coolers are powered by less than about 12volts of direct current. The thermoelectric coolers are attached toinsulated wires which are connected in parallel; and the thermoelectriccoolers are mounted on a heat exchanger to facilitate thermalconductance from the case.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates a perspective view of the personal computer showingthe cooling panels.

FIG. 2 schematically depicts an array of the thermoelectric coolerswired in parallel.

FIG. 3 depicts a single thermoelectric cooler between hot and cold sideplates.

FIG. 4 depicts a thermoelectric heat pump module with heatsink.

FIG. 5 presents the steps to cool a computer with a thermoelectriccooling panel.

DETAILED DESCRIPTION OF THE INVENTION

A cold plate cooling device that employs solid-state electronics, alsocalled a thermoelectric cooling panel, has been developed that isadaptable to personal and laptop computer cases to cool the internalcomponents without the noise of fans or pumps and without moving fluid,such as active cooling where water, for example, may leak from thecooling circuits. FIG. 1 presents a personal computer with cooling 2.The cooling panels 14, 16 of FIG. 1, comprise a plurality ofthermoelectric coolers 40, as presented in FIG. 3, that are conductivelymounted, preferably with Arctic Silver Thermal adhesive, on a thermallyconductive plate that is adapted to mount on a computer panel,preferably a side 4 or top 10, for example, of a personal computer casethat has a bottom 12, front 6, two sides 4, and a back 8. Thesolid-state electronics are essentially bimetallic thermocouples thatare powered with DC power to create a Peltier junction cooling effect.

The personal computer of FIG. 1 also presents an air intake hole 18 thatmay optionally be employed as well as an air exhaust hole 20 which maybe employed with an internally mounted fan to force air to flow throughthe case as a supplement to utilization of the cold plate cooling device14, 16. It is also conceived that in alternative embodiments, aninternal fan may be employed to direct cooled air to specific hotcomponents, such as a central processing unit chip. Generally it ispreferred that the personal computer case be sealed to prevent air flowinto or from the interior of the case, thereby retaining the cooled airinside the case, as well as minimizing the supply of moisture laden airto the inside of the case, which may then condense if the temperature ofthe cooled air or computer components inside the personal computer caseare below the dew point. It is preferred that the minimum cooledtemperature be maintained above the dew point, which is accomplished byan optional humidity sensor in a temperature control circuit.

Also presented in FIG. 1 is a direct current power supply 22 that isconnected to each of the thermoelectric cooling panels 14, 16 by powersupply leads 24. Each power supply lead contains both a positive and anegative lead to supply dc power to the cooling devices 14, 16.

The thermoelectric coolers 40, FIG. 3, are solid state heat pumps. Heatis “pumped” from the cold surface 42 to the hot surface 44 when a DCcurrent is applied to the device 40. A heat sink 56, FIG. 4, is requiredon the hot surface 44 to effectively remove the heat pumped from thecold surface 42. A no-load temperature differential of up to 65° C. withefficient heat removal is obtainable. The two greatest concerns forreliability are overheating and breakage. The junction surface is of aceramic material which is easily broken. Heat generated by the pumpingaction is removed with a heat sink 56. The modules will preferablyoperate with voltages from 3 to 12 volts. At higher voltages, with theincrease in current, the thermoelectric cooling panel 14, 16 must beappropriately sized.

The thermoelectric heat pump module with heatsink 54 is generallyillustrated in FIG. 4. The high thermal conductivity cold plate 58 isselected from the group of thermally conductive materials, includingcopper, aluminum, brass, stainless steel, beryllium, and titanium, andis preferably ⅛-inch thick copper or ¼-inch thick aluminum, and mostpreferably aluminum because of its cost, lightweight and resultingadvantage in handling and mounting. In a preferred embodiment, bothsides of the conductivity junction are coated with a thin layer of aheat sink compound (not illustrated) to facilitate thermal transfer.

Electrically insulated power leads 46 supply DC current to thethermoelectric heat pump module with heatsink 54. The cold plate 58 isplaced toward or against the computer to conduct heat from the hotcomputer through the cooling device to the heatsink 56 and then to thesurrounding environment, generally ambient or cooled air.

The thermoelectric cooler 40 is presented in the assembly 54 of FIG. 4as cooler assembly 60. The cold plate 58 is fixedly mounted to the heatexchanger 56 by means of thermally insulated standoffs 52, which arepreferably nylon hardware, but which in an alternative embodiment may bestandoffs that are thermally insulated with insulating washers. Toincrease thermal exchange efficiency and to prevent moisturecondensation on the cold surface 42 or on other cold parts of thethermoelectric heat pump 54, a vapor barrier 50 is applied which ispreferably an RTV silicone sealant.

Illustrated in FIG. 2 is a thermoelectric heat pump module 54 placementand wiring presentation generally 30, that illustrates thermoelectriccooler 32 placement for a 4 by 7 rectangular matrix. It is known by theinventor that the arrangement of modules 54 need not be rectangular,square or any regular geometric pattern and that this arrangement isillustrative only of a parallel wiring diagram where seven coolers 32are on presented in each row. While it is known that the coolers 32 maybe wired partially in parallel or series, it is preferred that eachcooler 32 be independently wired in parallel and be powered by a DCpower supply by an electrically conductive, insulated positive side wireconnector 34 and a negative side wire connector 36.

The thermoelectric cooling panel 14, FIG. 1, is preferably designed as aretro-fit to attach to the side of a personal computer or to the bottomside of a laptop computer. The attachment to the side is preferablyachieved with bolts, although in an alternate embodiment attachment isachieved by means of Arctic Silver 5 Thermal Adhesive, from ArcticSilver Inc, Visalia, Calif., a silicone gasket plus a thermallyconductive epoxy is employed. Arctic Silver is a preferred conductiveepoxy. The cold side of the thermoelectric cooling panel 14 is spacedabout ⅛-inch to ⅜-inch from the side 4 of the computer to create a spacebetween the cold sink and the side of the computer 4. It is beneficialthat the panel 14 be as intimately and as closely mounted to the side 4as possible to achieve efficient thermal transfer from the case. Thecomputer case is sealed with a silicone to close all potential airleaks. In an alternative embodiment, the entire side of the computer isreplaced with a cooling panel 14.

It has been found that thermoelectric heat pump modules from Mean Well,model SP-300-12, work well at 12 volts or less.

The method steps to cool a computer with a thermoelectric cooling panelare presented in FIG. 5.

In step 1 a computer having a case is provided for cooling. Athermoelectric cooling panel is selected that will fit to at least oneside of the computer case. In step 2, the thermoelectric cooling panelis powered by a DC power source and consists of a plurality ofsolid-state thermoelectric coolers that are wired in parallel.

In step 3 the thermoelectric cooling panel is attached to the computercase with a thermally conductive epoxy, preferably Arctic Silver Thermaladhesive, to assure good thermal conductivity of heat from the case andthrough the thermoelectric panel to the heat sink and then to theambient outside environment.

The computer case is sealed in step 4 to prevent cooling loss via airleakage from or into the case. In step 5 the ambient and dew pointtemperatures inside the computer case are monitored. The temperature ofthe thermoelectric cooling panel is maintained above the dew pointtemperature inside the case to prevent moisture condensation inside thecase, step 6.

Lastly, in step 7, the computer is turned off, if the ambienttemperature exceeds a set point value thereby avoiding damage to theinternal components of the computer.

Thus, in accordance with this invention, it is now possible to maintaina computer at a desired operating temperature using solid-stateelectronics without active cooling, such as air or fluid exchange. Thisis surprising since known cooling techniques rely on forced air orflowing water to cool the computer components.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is therefore to beunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

1. A structure, comprising: a cooling panel that is adaptable to attachto a personal computer case; said cooling panel comprised of a pluralityof solid-state thermoelectric coolers; said thermoelectric coolerspowered by less than about 12 volts of direct current; saidthermoelectric coolers attached to insulated wires which are connectedin parallel; and said thermoelectric coolers mounted on a heatexchanger.
 2. The structure according to claim 1, wherein said heatexchanger is comprised of copper.
 3. The structure according to claim 1,wherein thermally conductive epoxy attaches said cooling panel to thecomputer case.
 4. The structure according to claim 1, wherein saidcooling panel is attached to the computer case with bolts.
 5. Thestructure according to claim 1, wherein said cooling panel is comprisedof thermoelectric coolers located between a cold plate that radiatesheat to the surroundings and a heatsink that contacts the computer case.6. A method of cooling a computer, comprising the steps of: providing acomputer having a case; selecting a thermoelectric cooling panel;attaching the thermoelectric cooling panel with bolts to the computercase; sealing the computer case to prevent air leakage; monitoringambient and dew point temperatures inside the computer case; maintainingthe temperature of the thermoelectric cooling panel above the dew pointtemperature; and turning the computer off if the ambient temperatureexceeds a set point value.